Moment analysis of rf parallel-plate-discharge simulations using the particle-in-cell with Monte Carlo collisions technique

Abstract

Self-consistent simulations of rf parallel-plate discharges using the particle-in-cell with Monte Carlo collisions technique are employed to calculate explicitly the terms in moment or fluid equations that are derived from the Boltzmann equation. Isotropic electron-neutral-species elastic and ionizing collisions and ion-neutral-species charge-exchange collisions are included in the simulation. Results indicate that the convective term in the electron momentum balance can be neglected over a wide range of conditions. This approximation is also reasonable for ions when the sheaths are collisional. An analysis of terms in the electron energy balance indicate that heat conduction is important. However, the common expressions for heat conduction, such as the Fourier heat conduction, are not particularly accurate. The primary components of electron heating come from friction (collisional or Ohmic) and pressure work terms. For the particular model gas considered in this study, the collisional term is dominant for conditions when the product of pressure and gap is greater than 0.4 Torr cm. © 1993 The American Physical Society.